Re: Memory management under Oracle 9i

From: Pete Sharman <peter.sharman_at_oracle.com>
Date: 27 Jun 2002 09:34:50 -0700
Message-ID: <affera01eko@drn.newsguy.com>

In article <3d1b2e23$0$28003$afc38c87_at_news.optusnet.com.au>, Nuno says...
>
>In article <3d1b26b4$0$8505$ed9e5944_at_reading.news.pipex.net>, you said
>(and I quote):
>> I don't believe that zero is a valid value for the java pool - it wouldn't
>> be in 8i.You should check the docs for the minimum allowed value for 9i in
>> 8i I think you can get it down to 1meg. I'm not sure about the large pool
>> either.
>
>IIRC, in some cases setting these parameters to 0 means: use default.
>In others, it means: use as much as needed or available.
>
>Wouldn't this be the case here?
>I mean, Java would use the default (whatever that is) and
>large pool would allow for max virtual memory.
>
>--
>Cheers
>Nuno Souto
>nsouto_at_optushome.com.au.nospam

Straight from the 9.2 doc set:

JAVA_POOL_SIZE
Parameter type Big integer  

Syntax LARGE_POOL_SIZE = integer [K | M | G] **LARGE????  

Default value 24 MB, rounded up to the nearest granule size  

Parameter class Static  

Range of values Minimum: the granule size

Maximum: operating system-dependent  

JAVA_POOL_SIZE specifies the size (in bytes) of the Java pool, from which the Java memory manager allocates most Java state during runtime execution. This memory includes the shared in-memory representation of Java method and class definitions, as well as the Java objects that are migrated to the Java session space at end-of-call.

OK, so here's what I have for my 9.2 database after starting it with an spfile without any %POOL_SIZE parameters:

SQL> select name, value, isdefault, ismodified, isadjusted   2 from v$parameter
  3 where name like '%pool_size';

NAME                           VALUE      ISDEFAULT ISMODIFIED ISADJ
------------------------------ ---------- --------- ---------- -----
shared_pool_size               8388608    TRUE      FALSE      FALSE
large_pool_size                0          TRUE      FALSE      FALSE
java_pool_size                 25165824   TRUE      FALSE      FALSE
global_context_pool_size                  TRUE      FALSE      FALSE
olap_page_pool_size            33554432   TRUE      FALSE      FALSE

SO let's try setting JAVA_POOL_SIZE to 0:

SQL> alter system set java_pool_size = 0 scope=both; alter system set java_pool_size = 0 scope=both

                 *

ERROR at line 1:
ORA-02095: specified initialization parameter cannot be modified

Fair enough, it's static.

SQL> alter system set java_pool_size = 0 scope=spfile;

System altered.

SQL> shutdown
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area 51452388 bytes

Fixed Size                   453092 bytes
Variable Size              25165824 bytes
Database Buffers           25165824 bytes
Redo Buffers                 667648 bytes

Database mounted.
Database opened.
SQL> select name, value, isdefault, ismodified, isadjusted   2 from v$parameter
  3 where name like '%pool_size';

NAME                           VALUE      ISDEFAULT ISMODIFIED ISADJ
------------------------------ ---------- --------- ---------- -----
shared_pool_size               8388608    TRUE      FALSE      FALSE
large_pool_size                0          TRUE      FALSE      FALSE
java_pool_size                 0          FALSE     FALSE      FALSE
global_context_pool_size                  TRUE      FALSE      FALSE
olap_page_pool_size            33554432   TRUE      FALSE      FALSE

So it's not picking up the defaults. Now I seem to remember someone saying to me once you SHOULDN'T do this, because something won't work any more. Can't remember what though, so maybe I'm incorrect on that.

HTH. Additions and corrections welcome.

Pete

SELECT standard_disclaimer, witty_remark FROM company_requirements; Received on Thu Jun 27 2002 - 11:34:50 CDT